1. Field of the Invention
The present invention relates generally to closed containers used for the transport and storage of goods. More specifically, the present invention relates to an intermodal freight container for use in over the road, rail, and oceanic shipment of goods.
2. Description of the Related Art
Relatively large freight containers for the interstate and international shipment of goods have evolved to a relatively few standard sizes. Most of the dimensions used for container construction are the result of federal government standards or requirements and/or international standards and agreements, as such containers commonly travel throughout the U.S. and the world. As a result, various regulations and agreements have been developed regarding the size and configuration of containers used for such shipments in order to facilitate the carriage of such containers by ship, rail, and truck.
One of the most critical standards is the maximum permissible external width of such containers, with the limitation being primarily due to maximum vehicle widths when such containers are used as semitrailers for over the road shipments. In the U.S., federal rules limit the maximum external width of a vehicle used in interstate commerce to eight feet, six inches (102″) without a special permit. Most states have the same requirements. International standards are in very close agreement, limiting the external width of such containers to 2.6 meters, or about 102.36 inches. This 2.6 meter (102.36 inches) maximum width is seen to meet the U.S. standard of 102″.
No standards have been developed for the internal dimensions of such containers. The internal dimensions and resulting volume are strictly up to the manufacturer of the container so that the thickness and dimensions of the container depend upon the materials used to construct the container. However, a container with maximized internal dimensions is generally desired, in order to maximize the volume of cargo or freight that may be carried therein.
The standard freight container sidewalls are commonly constructed of relatively mild steel for economy, and as a result must use relatively thick steel panels having relatively deep corrugations to provide the required strength. Typically, the walls of a conventional container are nearly two inches thick, generally being within about one sixteenth of an inch of that dimension. The result is that the two sidewalls of the container take up nearly four inches of lateral width, limiting the internal width of the container to about 98.5 inches. While this may not seem to be a great deal of difference when the maximum permissible overall width of 102.36 inches is considered, it can make the difference between a load that just fits laterally within the container and another load configuration that results in a considerable amount of wasted interior volume in the container.
As intermodal containers have become standardized, so also have pallets used for the carriage of loads within such containers. Certain international standards have been developed for the horizontal dimensions of such pallets, with the standard dimensions being 80×120 cm (31.5×47.24 inches) and 100×120 cm (39.37×47.24 inches). In addition to these international standards, a de facto standard used in the U.S. is 44×56 inches. The 44×56 inch pallet finds use almost entirely in the U.S., with this pallet size seeing practically no international use.
The internal width of conventionally constructed containers is about 98.5 inches, as noted further above, or about 2.502 meters. As a result, it is impossible to fit conventional pallets of any standardized size or shape across the width of a conventional container without incurring considerable wasted lateral space. Two international standard pallets, each having a length of 120 cm (1.2 meters), may be placed laterally end-to-end to span 2.4 meters across the 2.5-meter internal width of a conventional container, with the resulting 0.1 meter (about 3.94 inches) not being particularly significant. Similarly, three international standard pallets may be placed side-by-side to span 2.4 meters.
However, the de facto U.S. standard size pallet of 44×56 inches cannot be conveniently arranged within the 2.5-meter or 98.5 inch nominal internal width of a conventional intermodal freight container. The placement of such pallets with their largest dimensions disposed laterally within the container results in over thirty inches of unused lateral space. The placement of two such pallets side-by-side is somewhat more efficient, resulting in a total width of 88″, but this still results in over ten inches of wasted lateral space within the container. When such pallets are placed longitudinally within a conventional container, their 56″ lengths define the number of pallets that may be placed longitudinally within a container. A conventional 53-foot long container has an internal length of about 52′, 8″, or about 632″. A total of eleven pallets placed end-to-end have a total length of 616″, leaving about sixteen inches of unused space for two rows of eleven pallets each, or twenty-two pallets in a 53-foot long conventional container.
However, if the container could be widened internally to span 100″, then U.S. standard pallets could be staggered with one pallet placed longitudinally and another placed laterally alongside. The total width of such an arrangement is 56″ plus 44″, or 100″. Groups of four pallets may then be arranged in square planforms of 100″ on a side, i.e., “pinwheeled,” to fill all of the available lateral space in such an internally widened container, leaving only a twelve-inch square open area within each group of four pallets. Six such groups of four pallets in each group would comprise twenty-four pallets having a total length of 600″, and could be placed easily within the 632″ internal length of a 53-foot long container. This would result in about nine percent more palletized freight capacity for such a container using U.S. standard pallets of 44×56 inches for an increase in internal container volume of only about one and one half percent, with the greater capacity resulting in a corresponding increase in profitability for the shipping company.
A number of different freight container configurations have been developed in the past, as noted further above. An example of such is found in German Patent No. 3,835,671, published on Apr. 26, 1990, which describes (according to the English abstract and drawings) the use of panels cut from a roll of sheet metal having a standard width for the construction of a container. The panels are cut to lengths equal to the height of the container, and assembled along their mutual lateral edges to form the desired length for the container.
None of the above-described inventions and patents describes the instant invention as claimed. Thus, a freight container solving the aforementioned problems is desired.